Electric control apparatus



Sept. 29, 1931. G. soMAJNl ELECTRIC CONTROL APPARATUS Filed Jan. .19. 1929 3 Sheets-Sheet 1 Sept. 29, 1931. G. soMAJNl ELECTRIC CONTROL APPARATUS Filed Jan. 19, 1929 3 Sheets-Sheet 2 3mm/Lto@ G/CUMU SUMJN/ Sept. 29, 1931.4 G. soMAJNl ELECTRIC CONTROL APPARATUS Filed Jan. 19, 1929 5 Sheets-Sheet :5

FIG. 3.

GIACOMO SOMJN/ Patented Sept. 29, 1931 PATENT YorrlcE Giacomo serum, oF MILAN, ITALY ELECTRIC CONTROL APPARATUS Application led January 19, v1929, Serial No. 333,605, and in Italy Jan-nary 81, 1928.

to one or more compound wound traction motors, so that during the starting of the said motors they are submitted to a scale of progressively increasing voltages, it is possible to start', say, a train, without employing rheostats. Similarly, a train may bebraked a very low `speed by submitting the motors in 2 like manner to a correspondlng scale of decreasing voltages.

l In apparatus ofthis kind, regeneration is,

of course, obtained, the said regeneration ben ing automatic; that is to say, there is no need for any particular operation to be elected bv the motormanin order to regenerate, since the same positions of the controller serve alike for starting and braking, regeneration being able to occur in any working positionl of the 39. controller. v

Further, in order to reduce the peaks of currentin the motors and to avoid consequent jerking, it is-also known to insert a small rheostat in thearmature circuit of the motors, the said rheostat remaining in circuit during the passageffrom one voltage to another, and being short-circuited automatically by a special differential relay when the current has diminished tvo-predetermined value.

o With apparatus in accordance with the present invention the currentpeaks which occur during passage from one voltage to another are still further reduced, and thus the running of the vehicle to be controlled is rendered more regular both in starting and braking.

The compound wound motors used in multiple-voltage regulation systems, such as the dynamotor system referred to, undergo a l diminution ofthe strength of the magnetic field when the current, flowing throu h its armature, is interrupted. If now onet rows a pressure upon them greater than that previously applied, so that a stron er current will pass through said armature, tiiis pressure will finda weak field, and in the first moment a current far greater than the normal one will pass through the motor. This current increases the field strength and the current itself diminishes to the normal value; but the C0 transient increase of current has caused an increase of'drivin couple and also jerking of the vehicle. W ile braking, the motor operates as a generator and its series excitation reduces its field strength. An interruption of armature current permits an increase of field strength and when a pressure lower than the first one applied is thrown upon thearmature, the motor'will generate a stron current. This current will thereafter re uce the 7 strength of the field' and then also the current itself, but, in the first moment, there will bel a currentpeak and then a jerkingof the vehicle, as stated before.

The object of lthe present invention is to provide a system of motor control which avoids these drawbacks. According thereto, the shunt excitation of the motors is temporarily increased when the pressure applied to the armature is increased while accelerating and said excitation is temporarily diminished when the pressure applied to the armature is diminished while braking. Thus, when the different pressure is applied to the motor, it is capable of withstanding it without producing current peaks and jerks. Aftera certain time, when the current is diminished and the motor speeded up, the excitation is again made normal and the motor then supports the new pressure applied without any trouble.

The various novel features of the invention will lappear from the description and drawings, and.' will be more particularly 95 pointed out in the claims:

Figure 1 is a diagrammatic View of a motor control having aresistance in the shut excitation, and a lost-motion controller drum shortcircuiting said resistance. A differential re- 1M 'lay of known type short-circuits another resistance inserted in the armature circuit..

Fig. 2 is a similar view, 1n which both the resistances of the shunt excitation and ot the armature circuit are short-circuited, each by a lost-motion controller drum. Y

2 operating circuit. l A l Fig. v3 isV another diagrammatic v1ew,'1n

Y said motor being `subjected to,'for example,

F ig. 2a is a similar 4view showingna relay whichV the shunt excitation circuit of the motor has a resistance which is short-cire,

cuited by a lost-motion drum, whereas a resistance and a regulating motor are inserted in i the armature circuit, said resistance being,l by wa of example, short-circuited by alnlown di erential relayand the regulating motor becoming short-circuitedby a lost-motionl drum.

In V the arrangement shown in Fig. 1, it'V is' assumed, for the sake ofl simplicity, thatthere is merelya single motor to be'reg-*ulatech` the voltages' oLtV -0-125-250`-"375`500 during starting and conversely to voltages ot G-375'-250--125f-Ol duringbraking. n n VC is the drumof themain controller,and

is providedwith Abrushes O, 125,375, 500, per'- manent-ly maintained bya multiple-voltageY supply, vfor example, a dynamotor, atV the voltagesO, 125,V 375, 500, and with brushesl and 8 from which the armature circuitlof the strongestfshunt'excitation (i.V e; resistance?` motor is fed.

'If the drum is 'turned clockwise, i. e. rsuch' 1 that the brushes 1, 8, 125 lpass from contactsV Oto contact/SI, then'to contacts' II, and so on, Vthe tongue p is jdrivenby the wall of the 'groove of disc Q and the relative position ofthe drilinsis such that va Set of lcontactsn Y drumCcorresponds to aninterval between vtwosets of contactsonV drum C. It, on the Vother hand, the drum is turned countercloclwise, then tongue pl is driven by the wall if ofthe groove, and the relative posit-ion be. tween the drums is such that sets of contacts on both drums Cand C correspond one to another. j Y I l The first direction of rotation corresponds to starting andit willbe seen from theV ligure that `the weakest shunt excitation i. e. resistf ance 1' inserted) is obtained when the drum*- C is in one of the setting positions wliile'the shortcircuited) is obtained during the pas'- sage from one settingfpositionto the next. In motoring, themo'tor lis thus over-excited during passage fromv one setting posit-ion to the other, 'y l The Vsecond. direction of rotation corresponds Vto braking. In` this direction, the

contacts upon the drum C are displaced towards the left with respect to the position indicatedin the. drawings to an extent necessary to ensure that the contacts upon the drum Clie on the same mean line, as the contacts upon the drum C,v The lirst rotation of Ving with the groove of the first disc.

drum C with respect to drum C', duc to the relative motion allowed by the claw coupling M, must obviously equal halt' the angular distance bet\\'een..each setting' position and the f'ellowiug Thus, underthese comlitions, the motor becomes ove1=e.\cited While the drum Ck is in any one ot the setting positions, and 'undeikexcitedj during "passage from one position to the next, so that the Ysaid motor becomes underexcited before the prin- -cipal contacts are established'and the braking current exerts its underexciting action.

'ik similar phenomenon is produced during starting, the motor being over-excited before the compound action exerted:V by the starting current is produced, after the principal circuits have been closed. The advantagesobtained tromthe present invention are:

(un)t The currentp'eaksarereduced, since.y f Y the closing` of the principal circuits after each j 85 chang-cot connections is preceded lby. a state ot' over-excitation of thelmotors in motoring' andl under-excitation in'braking. Y

(Z2) The current to 'be interrupted is lreduced partly by the automatic introduction ofthe resistance R and partly by the .variationjinexcitation referred to'in (aiabove. v-

c) l VThere is provided greater excitationy durmgbralnng than during motoring. During motoring, indeed,` the seriesV excitation is added tothe shunt excitation, whereas, during'braking, it isrsubtracted. V

A similararrangement may be employed for shorticircuiting resistanceR ofthe arma ture circuit, which, in Fig. 1, was assumed to be short-circuited by a common differential relay I.; F ig. 2 shows such an arrangement, in which an .auxiliary drum Cfcarries slidingr4 contacts'which short-circuit ,brushes 6, 7 and thus'resistance R. .This drum is operatively conne'cted with'drum C by means of a: claw coupling N similar to that of M described 4 above. v The vsettin,f f positions of drum' C are split in two andthe contacts on drumrCr arev couplings each comprise, 4as'stated above, two discs, one of which presents' a dlametricalV groove, while the other has a tongue engag- The groove is larger than the tongue, so that a certain relative motion isgallowe'd between a" couple ofthe engaging discs. Drums C', C

then ,follow thefrotation of drum C in whatever direction with a certain lag. The relative motionl'between drumsC and C is kept equal to half* the ang-le between two `successive analogous setting positions ot `the controller,

such as I and II or II andIII. The relative motion-VbetWeen-drinns C and C is kopt equal to the angle between two successive setting positions of said controller, such as I and I', II and Il', etc.

On drums C and C contacts are provided, adapted to short-circuit the fixed brushes. Contacts of drum C short-circuit brushes 10, 11 and then resistance r inserted on the shunt circuit of the excitation ofthe motor, and contacts of drum C short-circuit brushes 6, 7 and then resistance R inserted in the armature circuit.

Thus, due to the relative motion between the drums connected by the claw coupling M, resistor r is made' operative While motoring in every setting position of the controller,

while it is short-circuited during the passage from one position to another, such as I-II, II"-III, III-IV, i. e. when the armature circuit is broken, while resistor 1' is made operative during said passages andshort-circuited in all of the setting positions while braking. The relative angular position between drums C and C is such that while motoring R is made operative in setting positions as I, II, III, IV, and short-circuited in the others, which are the second met with of double setting positions, and while braking R is made operative in such setting positions as I', II, III, IV', which are then the first position met with, and short-circuited in the` others. Moreover, both while motoring' and braking, R is made operativey during the switch-over ofthe armature circuit.

For clearness sake, the relative positions of drums C and C, with respect to main drum C while motoring (clockwise rotationof C), are shown in full lilies; and the same positions while braking (counterclockwise rotation of C) are shown in dotted lines. In order that the relative position between thel various drums be maintained during rotation, it is not suicient -to provide a notched disc E on the main controlling drum C, and a spring catchWV to stop the main drum in the exact positions. One must also provide means adapted to prevent the auxiliary drums C', C from running before their theoretical posi'tions, which are conveniently displaced backwards With respectto that of the main drum C. Such means consist of notched discs K and K for the auxiliary drums C', C and corresponding spring catches W and W adapted to compel said drums to keep the correct position. For this purpose stops are mounted. on the casing of the controller and engage with the vnotches of said discs; whereunto said stops are provided with a strong spring capable of exerting on the notched disc a sufficient resistance, i. e. a moment of resistance greater than the moment of torsion exerted on the disc by the friction lx tween the elements of the claw coupling (M or N). f

Let us suppose the circumference divided into 27 parts. Disc K will only `be provided with such notches as are necessary for fixing th e positions O-I-I-lI-II-l ll- III-IV-IV, while each of the discs K and K'has 27 notches so that their setting is always definite, for in the case exemplified, the lost motion at every rotation reversal of C isof three steps for C and of only two ste s for C.

s tothe operation of the device it is enough to point out that both during the starting period and during braking, each voltage is applied to the armature first with R switched-in and after with R short-circuited, what causes a reduction of the current jerks on stepping from one applied voltage to the other.

Naturally this arrangement is also applicable to the case in which two or more motors are coupled in series or in parallel. The nulnber of voltage steps to apply to the armatures of said motors can also vary; this requires only a variation in the number of contacts mounted on drum C and in the number of control positions, but not in the structure and relative bearing setting of drums C,-C, in which only the number of contacts has to be correspondingly increased.

A part R of the resistances of the armature circuit can also be controlled bv a relay I operating before or after (see ig. 2a), while the other part will be controlled directly by the controller. If said relay must operate before for short-circuiting the part of R depending on the same, the contacts e which operate the differential relay must be fixed on drum C and must be switched in cir? cuit either in positions I-II-III-IV or in positions I-II-III'IV.

If on the contrary, said relay must operate after. said contacts will have to be arranged on C in a similar way to those short-circuiting brushes 6*-7, so that on starting, the differential relay operates only in I*II grr-IV and in braking in I-II-III- Finally it must' be pointed out that a motor excited in series operates exactly in the same way as a simple resistance. Consequently resistance R can be either totally or partially replaced by a series motor Z (see Fig. 3), capable of creating a proper counter-electromotivel force, said motor being keyed on the shaft of the dynamotor D operating as voltage-splitter and providing the fundamental voltages 125, 250 and 375.

Said motor will be switched in the circuitv in the exact point in which is inserted that part of resistance R which hasto be replaced by said motor. In such a case the energy absorbed by said motor is not totally spent in heat: on the contrary it is regenerated and sent back'into the circuit through the dvnamotor operating as voltage-splitter. on whose shaft said auxiliary motor is keyed.

In Fig. 3, there is shown, by way of excuit of the latter there is a resistance -1' which 5 may be short-circuited by the auxiliary drum Y C of the controller. In the armature circuit are inserted a resistance R and a regulating motor Z. Resistance R may become shortcircuited by a differential relay I, such asare Vgenerally known; motor Z, instead,fis connected to another auxiliary drum C of the controller, which short-circuits it, as stated before. Y i i Y Y The motor Z is series excited and its `arma'- ture is keyed on the shaft of the dynamotor D, rotating,'therefore, at the same speed as the dynamotor, i. e. at a constant speed and Valways in the same sense. The insertlon of its field winding is such that for the given direction of rotation it'oper'ates as a motor, whatever the direction of the current may be; it generates, therefore, in any case a fall of pressure in the same direction of the current, whichpasses through it.V This results in an absorption of'an amount of energy VJfrom the current which is proportional to the current itself, and this energy is transmitted.l mechanically tothe dynamotor, which'transforms it again into electric current and supplies it to the main circuit. Thus motor` Z actsboth when motoringand when braklng as a regulator of current, and could bekept permanently in the circuit, thereby avoidlng the-short-circuiting means shown in Flg. 3.

If, on the contrary, one will short-circuit Z and R, as shown in Fig. 3, it should be convenient to maintain the motor in 'actlon longer than'the resistance. Therefore, relay I, short-circuiting the latter, should have its 40 voltmetric coil v supplied from the main drum C through contacts e, while theV amperemetric oneV a is inserted in the armature circuit of both motors.- Contacts e should for the same reason cover both positions I, II,

III and I,II, III.

` The aboveand many other modifications may be made in the specific means o f carry- A ing out the invention and allsuchwhlch come within the' spirit and scope of the invention are vbelievedY to be covered in the claims.

What I claim is :V 1. In a multiple-voltage system of motor control, including a Vsource of balanced multiple supply, a Ycompound wound motor and a `controller having a number of double settmg positions-for throwing upon said motor consecutively the diderent pressures A of the multiple supply, means to increase tempo- Y rarily the shunt'excitation of said-.motor when 6 said controller is throwing upon said motor a greater pressure and to decrease temporarily said shuntexcitation when said controller is throwing upon said motor a lesser pressure, a series wound motor mechanically connected with said source of multiple supi whereby the rotation of said auxiliary drum double position of rest which is reached,

`whethertheV rotation ofl said controller be clockwise or counterclockw'ise.

2.V In a multiple-voltage system of motor control, a source of multiple-'voltage supply, a motor having series and 'shunt field windings, a resistance in circuit with said shunt winding, a controller movable successively to a number of setting positions for throwing upon the motorV consecutively the different voltages of said supply, an auxilviary controller drum provided with a pair of brushes connected to the terminals ofsaid resistance, a plurality of contact elements' ar ranged on said auxiliary drum to short-circuit said brushes in certain angular positions of said drum, and a lost-motion driving connection between said auxiliary drum and said controller whereby Vwhen said controller is moved in a starting direction to increasethe voltage Vapplied to said motor, said resistance is short-circuited as said controller is moved from onesetting position to another, and upon moving said controller in a braking direction to decrease the applied voltage, said resistance is short-circuited in each set- 95 ting position of vsaid controller.

3. The combination specified in claim 2 wherein the lost motion coupling between the main'controller and the auxiliary drum comprises a disc keyed -to the shaft of the controller, a second disc keyed to the shaft of said drum, one of saiddiscs being provided with a toothed element arrangedto engage spacedY stop elementson the other disc, said stop elements being spaced, apart to permit `relative motion between` the two discs in different directions of rotation, 'and means for nor-r inally frictionally lholding Y said auxiliaryv drum against movement by said controller,

lags the' rotation of said controller in either direction of movement. l i i 4. In.a'multiple-voltagesystem of motor control, a source of multiple-voltage supply,

a motor having series and shunt'field wind- 115 ings, a resistance in circuit with Vthe series,Y winding, a controllerjmova'ble successively to a number or"y double setting positions forthrowing uponthe motorl consecutively the different voltages of said supply, andk means embodied in said controller for rendering said resistance effective in said armature circuit when said controller rests in the first of each of said double positions regardless of the direction of movement of sai'dcontroller, and means embodied: in said controller yto short-V circuit said resistance when said controller rests in the second of said double positions regardless of its direction of movement.

5. In a multiple-voltage system of motor control, including a source of balanced multiple supply, a compound Wound motor and a controller having a number of double setting positions for throwing upon said motor 5 consecutively the different pressuresof the multiple supply, means to increase temporarily the shunt excitation 'of said motor when said controller is throwing upon said motor a greater pressure and to decrease temporarily said shunt excitation when said controller is throwing upon said motora lesser pressure, a resistance connected in series with the motor armature, and means operated by said controller for inserting Said resistance in the armature circuit of said motor in the first of each of said double setting positions 'which is reached, and for short-circuiting said resistance in the second of cach of said double positions, regardless of the direction of rotation of said controller.

6. In a multiple-voltage system of motor control, `a source of balanced multiple-voltage supply, a motor having series and shunt field windings, a controller movable successively to a number of double setting positions for throwing upon the motor consecutively the different voltages of said supply, a resistance in circuit with said shunt winding, an auxiliary controller drum having a number of setting positions corresponding in angular displacement to the angular displacement between the double setting positions on said controller, circuit connections to l said auxiliary drum controller for short-cirw cuiting said resistance in said setting positions, a lost motion driving connection between said controller and said auxiliary drum whereby when said controller is moved in a direction for increasing the voltage applied to said motor, said resistance is short-circuited temporarily as said controller passes from a lower voltage to a higher voltage, and when said controller is moved in a direction to decrease the applied voltage, said resistance is short-circuited in each setting position of said controller, a resistance connected in the armature circuit of said motor, a second auxiliary drum having a number of setting positions corresponding in angular displacement to the angle between the double setting positions on said controller, circuit connections for short-circuiting said second resistance by said second auxiliary drum in said setting positions, and a lost-motion driving connection between said controller andsaid second auxiliary drum whereby said second resistance is short-circuited when said controller rests in the second of said double positions regardless of its direction of movement.

In testimony whereof I aHiX my signature.

GIACOMO SOMAJNI. 

